Acidic polycyclic ether antibiotic

ABSTRACT

An acidic polycyclic ether antibiotic, having structure established by X-ray crystallography, is formed by fermentation of a novel microorganism, Actinomadura sp. ATCC 55080. This novel antibiotic is useful as an anticoccidial in poultry, in the prevention and treatment of swine dysentery and as a growth promotant in cattle and swine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 of PCT/US91/06084, filed 30 Aug. 1991, which is a continuation of U.S. application Ser. No. 07/592,429, filed 4 Oct. 1990 (now abandoned).

BACKGROUND OF THE INVENTION

The present invention concerns a new acidic polycyclic ether antibiotic having the formula: ##STR1## having relative stereochemistry as shown; pharmaceutically acceptable cationic salts thereof; nutrient feed compositions comprising said antibiotic for poultry, cattle or swine; its use as an anticoccidial agent in poultry, in the treatment or prevention of swine dysentery, or as a growth promotant in cattle or swine; a fermentation method for its preparation; and the Actinomadura sp. microorganism which produces said antibiotic in said fermentation method.

The compound (I) is a new member of the acidic polycyclic ether group of antibiotics. This family includes such well known agents as monensin (The Merck Index, 11th Ed., Merck and Co., Inc., Rahway, N.J., 1989, monograph no. 6157), nigericin (loc. cit., monograph no. 6457), narasin (loc. cit., monograph no. 6339), lasalocid A (loc. cit., monograph no. 5243), and salinomycin (loc. cit., monograph no. 8305). The subject has been reviewed by Westley, "Polyether Antibiotics", Adv. Appl. Microbiol., vol. 22, pp. 177-223 (1977). These compounds are generally known as coccidiostats, as feed additive-growth promotants, and/or as agents useful against swine dysentery.

SUMMARY OF THE INVENTION

A culture of Actinomadura sp. ATCC 55080, when fermented under aerobic conditions in aqueous media, produces a new acidic polycyclic ether antibiotic, a compound having the formula (I), as specified above.

The present invention is directed to said compound of the formula (I), including the pharmaceutically-acceptable cationic salts thereof, and to a process for its preparation which comprises fermentation of said Actinomadura sp. ATCC 55080 in an aqueous nutrient medium comprising an assimilable source of carbon and nitrogen until a recoverable amount of said compound of the formula (I) is formed, preferably under submerged aerobic conditions. For use as an anticoccidial agent, in the prevention or treatment of swine dysentery, and/or as a growth promotant, the compound (I) can be separated from the fermentation and isolated in substantially pure form. However, it is alternatively used in crude form, for example, in precipitated form admixed with mycelium (recovered by filtration of the fermentation medium), or in solids obtained by spray- or freeze-drying the entire fermentation medium.

Said pharmaceutically-acceptable cationic salts include, but are not limited to, those of sodium, potassium, calcium, ammonia, N,N'-dibenzylethylenediamine, N-methylglucamine (meglumine) and diethanoiamine. The preferred cationic salts are those of potassium and sodium.

The present invention is also directed to nutrient feed compositions, one for cattle or swine which comprises the compound of the formula (I) in an amount effective to promote growth and/or improve the feed utilization of said cattle or swine, or to prevent or treat dysentery in swine; and the other for poultry which comprises the compound of the formula (I) in an amount effective to control coccidial infection in said poultry.

The present invention is further directed to a method for promoting growth and/or increasing the efficiency of feed utilization in swine or cattle which comprises administering to said swine or cattle a growth promoting or feed-utilization efficiency promoting amount of the compound of the formula (I), particularly in the form of a nutrient feed composition; to a method for preventing or treating dysentery in swine which comprises administering to said swine a compound of the formula (I) in an amount effective in preventing or treating said dysentery in said swine; and to a method for controlling coccidial infections in poultry which comprises administering to said poultry an anticoccidially effective amount of the compound of the formula (I), particularly in the form of a nutrient feed composition.

Finally, the present invention is directed to a biologically pure culture of Actinomadura sp. ATCC 55080, said culture being capable of producing the compound of the formula (I) in a recoverable quantity upon fermentation in an aqueous nutrient medium comprising assimilable sources of carbon and nitrogen; including said culture in freeze-dried form.

DETAILED DESCRIPTION OF THE INVENTION

The culture capable of producing the present polycyclic ether antibiotic of the formula (I) is designated Actinomadura sp., and has been deposited under the Budapest treaty in The American Type Culture Collection, Rockville, Md. as the type culture under their accession number ATCC 55080. The culture was accepted for deposit by the ATCC on 27 Jul. 1990. Permanency of the deposit of this culture at The American Type Culture Collection at Rockville, Md. and ready accessibility thereto by the public are afforded throughout the effective life of the patent.

This novel culture was derived from a soil sample collected in Ohno, Gifu Prefecture, Japan; and identified in the culture collections of Pfizer Inc. as N854-24 and as F. D. 28800. Its description and classification were provided by Dr. L. H. Huang. This culture was found to produce narrow dimensions of the hyphae typical of the actinomycetes, an aerial mycelium, and an unfragmented substrate mycelium. The results of the whole cell analyses further indicate that it belongs to the genus Actinomadura.

A slant culture of the microorganism on ATCC 172 media was inoculated into ATCC 172 broth and grown for four days at 28° C. on a shaker. It was then centrifuged for 20 minutes, washed three times with sterile distilled water, and planted on media commonly used for identification of members of the Actinomycetales.

The cultures were incubated at 28° C. and the results read at varying times, but most commonly at fourteen days. The colors were described in common terminology, but exact colors were determined by comparisons with color chips from The Color Harmony Manual, fourth edition. The methods of whole-cell amino acid and sugar analyses are those described in Becker et al., Appl. Microbiol., vol. 12, pp. 421-423 (1964), and in Lechevalier, J. Lab. Clin. Med., Vol. 71, pp. 934-944 (1968), respectively.

The culture was identified as follows:

Yeast Extract-Malt Extract Agar (ISP #2 medium, Difco)--Growth good; white, cream, pale gray, brown to dark brown (2 ca, 3 ne, 3 pg, 3 pi); raised, wrinkled appearing as confluent or isolated colonies; aerial mycelium white to pale gray (near gray series 3 eb) reverse yellowish, yellowish brown, brown to dark brown (2 ia, 3 nc, 3 ng, 3 pi ); no soluble pigment.

Oatmeal Agar (ISP #3 medium, Difco)--Growth moderate, greenish yellow (11/2 lc, 11/2 ne); slightly raised, smooth, with no aerial mycelium; reverse yellowish green to greenish yellow (1 lc, 11/2 lc); soluble pigment cream (2 ca).

Inorganic Salts-Starch Agar (ISP #4 medium, Difco)--Growth poor to moderate; colorless to cream (2 ca); thin, smooth, with no aerial mycelium; reverse same as surface; no soluble pigment.

Glycerol-Asparagine Agar (ISP #5 medium, Difco)--Growth poor to moderate; cream to pale orange-pink (2 ca, 4 ca); slightly raised, smooth, appearing as confluent or isolated colonies; no aerial mycelium; reverse same as surface; no soluble pigment.

Czapek-Sucrose Agar (Waksman, "The Actinomycetes", v. 2, medium #1, p. 328, 1961)--Growth poor to moderate; cream (2 ca); thin, smooth, appearing as confluent or isolated colonies; no aerial mycelium; reverse cream (2 ca); no soluble pigment.

Glucose-Asparagine Agar (ibid., medium #2 )--Growth moderate; pale green, yellowish green to green (1 ca, 11/2 ne, 11/2 pe, 1 lc); slightly raised, smooth, appearing as confluent streaks or isolated colonies; no aerial mycelium; reverse greenish yellow to pale green (1 ca, 1 lc, 11/2 ne); no soluble pigment.

Gordon and Smith's Tyrosine Agar (Gordon and Smith, J. Bacteriol., 69:147-150, 1955)--Growth poor to moderate; brown to dark brown (3 le, 3 lg, 3 ni); slightly to moderately raised, smooth to granular, appearing as isolated colonies with a few dots of pale gray aerial mycelium (3 dc); reverse yellowish brown to dark brown (3 ne, 3 ni, 3 el); soluble pigment yellowish (2 ic).

Calcium Malate Agar (Waksman, Bacteriol. Rev., 21, 1-29, 1957)--Growth scant; colorless to cream (2 ca); thin, smooth, appearing as isolated colonies; no aerial mycelium; reverse colorless, cream to yellowish (2 ca, 2 ga); no soluble pigment.

Casein Agar (Gordon and Smith, ibid.)--Growth moderate to good; dark yellowish (2 ic); moderately raised, wrinkled, with no aerial mycelium; reverse same as surface; soluble pigment yellowish (2 lc).

Bennett's Agar (Waksman, loc. cit., medium #30, p. 331)--Growth good; white, cream, yellowish, yellowish brown, brown to dark brown (2 ca, 2 ic 3 lc, 3 le, 3 ni); raised, wrinkled; aerial mycelium white; reverse yellowish, yellowish brown, brown to dark brown (2 ga, 3 ne, 3 ng, 3 ni); soluble pigment pale yellowish (2 ga).

Emerson's Agar (ibid., medium #28, p. 331)--Growth moderate to good; white, cream, gray to dark gray (2 ca, 2 ea, near 2 fe, 2 ih, 2 ml); highly raised, wrinkled, appearing as isolated colonies; aerial mycelium white to gray (near 2 fe); reverse yellowish, gray to dark gray (2 ga, near 2 fe, 2 ih, 2 ml); no soluble pigment.

Nutrient Agar (ibid., medium #14, p. 330)--Growth moderate; white; slightly raised, smooth, with white aerial mycelium; reverse cream (2 ca); no soluble pigment.

Gelatin Agar (Gordon and Mihm, J. Bacteriol., 73, 15-27, 1957)--Growth poor to moderate; brown to dark brown (3 le, 3 ni, 3 pn); moderately raised to raised; smooth to wrinkled, appearing as isolated colonies, with sparse white aerial mycelium; reverse brown to dark brown (3 ne, 3 ng, 3 pl); soluble pigment yellowish (2 ic).

Starch Agar (ibid. )--Growth moderate; brown to dark brown (3 ng, 3 pl); slightly to moderately raised, smooth to granular with pale gray dots (near 3 cb) of aerial mycelium; reverse brown to dark brown (3 lg, 3 pl); soluble pigment yellowish (2 lc).

Potato Carrot Agar (Lechevalier, Lab. Clin. Med., 71, 934-944, 1968, but use only 30 g. potatoes, 2.5 g. carrots and 20 g. agar)--Growth poor to moderate; yellowish green to greenish yellow (11/2 ca, 11/2 le, 11/2 ng); slightly raised, smooth to granular, appearing as isolated colonies; with sparse, white aerial mycelium; reverse same as surface; no soluble pigment.

Tap water Agar (2%)--Growth poor; colorless to cream (2 ca); thin, smooth, confluent or appearing as isolated colonies; no aerial mycelium; reverse colorless to cream (2 ca); no soluble pigment.

Gauze's Mineral Medium 1 (Gauze et al. Problems in the Classification of Antagonistic Actinomycetes, Engl. ed., 1957, p. 13)--Growth moderate, yellowish green (1 ic) with some grayish yellow dots (11/2 le), thin, smooth to granular; aerial mycelium none to sparse, not affecting colony appearance; reverse yellowish green (1 ic); soluble pigment cream (11/2 ca).

Gauze's Organic Medium 2 (ibid.)--Growth moderate to good; dark green, yellowish green to pale pink (1 ic, 1 lg, i ni, 4 ea, 4 ga), moderately raised; smooth, wrinkled to granular; aerial mycelium none to sparse, not affecting colony appearance; reverse same as surface; soluble pigment yellowish (2 ic).

Morphological Properties--The morphological properties were observed after 16 days of incubation on yeast extract-malt extract agar: aerial mycelium white, vegetative mycelium yellowish brown to brown; hyphae branched, 0.4 to 1.0 μm diam.; no spores were produced, even after six weeks of incubation on this and other media.

Biochemical Properties--Melanin not produced; hydrogen sulfide not produced; gelatin liquefied; esculin, hippurate and starch not hydrolyzed; organic nitrate but not dextrose nitrate reduced to nitrite; no growth and no decomposition on either Jensen's cellulose broth or Levine and Schoenlein's cellulose broth; peptonization and coagulation of milk; casein digestion positive; adenine, hypoxanthine, xanthine, urea, tyrosine and calcium malate digestion negative; resistance to lysozyme positive.

Carbohydrate utilization: glucose and rhamnose utilized; starch and trehalose doubtfully utilized; arabinose, fructose, inositol, mannitol, raffinose, sucrose, xylose, adonitol, cellobiose, dulcitol, erythritol, galactose, glycerol, lactose, maltose, mannose, melezitose, melibiose, α-methyl-D-glucoside, ribose, salicin, sorbitol and sorbose not utilized.

Utilization of organic acids: acetate, lactate, propionate, and pyruvate utilized; benzoate, citrate, dextrin, malate, mucate, oxalate, phenol, and succinate not utilized.

Acid production from carbohydrates: acid produced from glucose, arabinose, fructose, inositol, mannitol, raffinose, rhamnose, sucrose, xylose, adonitol, cellobiose, dulcitol, erythritol, galactose, glycerol, lactose, maltose, melezitose, melibiose, α-methyl-D-glucoside, ribose, salicin, sorbitol, sorbose, and trehalose; acid not produced from mannose and starch.

    ______________________________________                                         Temperature Relations                                                          21° C.                                                                            28° C.                                                                               37° C.                                                                           45° C.                                  ______________________________________                                         Poor to   Good         Good     No                                             Moderate  Growth       Growth   Growth                                         Growth                                                                         ______________________________________                                    

Cell Wall Analysis--The whole-cell hydrolysates contained meso-diaminopimelic acid, galactose, glucose, madurose and ribose.

The present culture is characterized by the white, pale gray to gray aerial mycelium; the yellow-green to green-yellow substrate mycelium; and the isolated colonies as a result of slow growth. The spores and spore chains were not observed on different media even after a prolonged period of incubation for six weeks. The following biochemical tests were positive: gelatin liquefaction; reduction of organic nitrate to nitrite; decomposition of casein, coagulation and peptonization on milk; resistance to lysozyme; utilization of glucose, rhamnose, acetate, lactate, propionate, and pyruvate. The whole-cell hydrolysates contained meso-diaminopimelic acid and madurose. Thus, this culture belongs to the genus Actinomadura.

The present culture resembles Actinomadura macra (Huang, L. H., Int. J. Syst. Bacteriol. 30: 565-568, 1980) in the color of the aerial mycelium and in most of the biochemical properties. However, on oatmeal agar and Gauze's medium #1 the substrate mycelium of the former is yellow-green but that of the latter is cream to faint pink and off-white to pale gray, respectively. In addition, A. macra produces hydrogen sulfide, decomposes tyrosine but not casein and utilizes sucrose but not rhamnose.

Compared with the present culture, Actinomadura pulveracea (Iwami, M. et al., J. Antibiot. 38: 835-839, 1985) differs in the positive utilization of sucrose and xylose and the positive hydrolysis of starch. The aerial mycelium of A. pulveracea is gray to blue rather than white to pale gray to gray. On glucose-asparagine agar the substrate mycelium of A. pulveracea is pink but that of the present culture is green-yellow to pale green.

The present culture is related to Actinomadura atramentaria (Miyadoh, S. et al., Int. J. Syst. Bacteriol. 37: 342-346, 1987) in most of the biochemical properties but differs in the production of melanin, the negative liquefaction of gelatin, and the negative utilization of rhamnose.

On the basis of the data presented above, the present culture N854-24 is considered as a new strain of the genus Actinomadura and designated Actinomadura sp. It has been deposited with the American Type Culture Collection under the accession number ATCC 55080.

The antibiotic compound (I) of the present invention is readily produced by the present Actinomadura sp. by growing at from about 24° to about 36° C. under submerged conditions with agitation and aeration on media consisting of carbohydrate sources such as sugars, starches, glycerol; organic nitrogen substances such as soybean meal, casamino acids, yeast extract; growth substances such as grain solubles, fish meal, cotton seed meal; mineral salts containing trace elements such as iron, cobalt, copper, zinc, etc.; and calcium carbonate or phosphates as buffering agents. After growth has been completed, the antibiotic is readily recovered by extracting the whole broth with an organic solvent such as n-butanol, methylisobutyl ketone, or chloroform at pH ranges from 4.0 to 8.0; by filtering off the mycelium, which contains the precipitated antibiotic, the filtrate being discarded; or by simply spray-drying or freeze-drying the whole broth. Alternatively, the mycelium or the whole dried broth is extracted with one of said organic solvents. The purified antibiotic compound, if that is desired, is isolated from the organic extract by standard methods of concentration, salt or free acid formation, chromatography, precipitation and/or crystallization, as exemplified below.

In the usual manner of carrying out the fermentation, an inoculum is first prepared by scraping vegetative cells, growing on a suitable media, from slants or Roux bottles which have been inoculated with Actinomadura sp. ATCC 55080. The resulting vegetative cells are in turn used to inoculate shake flasks or inoculum tanks, also containing suitable growth media. Alternatively, the inoculum tanks are inoculated from the shake flasks. Following a suitable growth period (generally 120 to 144 hours in shake flasks and 168 to 196 hours in inoculum tanks), a fermenter, also containing suitable growth media, is inoculated under aseptic conditions with vegetative broth from the shake flasks or inoculum tanks. Upon completion of growth (generally about 120-196 hours), the antibiotic compound is recovered in crude or pure form, as desired, by one or another of the methods generally described above, or by specific methods which are exemplified below.

The compound of the formula (I) is tested for in vitro antibacterial activity by standard methods in which the minimum inhibitory concentrations (MIC's) in mcg/ml against one or more microorganisms is measured. One such procedure is the one recommended by the International Collaborative Study on Antibiotic Sensitivity Testing (Ericcson and Sherris, Acta. Pathologica et Microbiologia Scandinav, Supp. 217, Section B: 64-68 [1971]), and employs brain heart infusion (BHI) agar and an inocula replicating device. Overnight growth tubes are diluted 100 fold for use as the standard inoculum (20,000-100,000 cells in approximately 0.002 ml. are placed on the agar surface; 20 ml. of BHI agar/dish). Twelve 2 fold dilutions of the test compound are employed, with initial concentration of the test drug being 200 mcg/ml. Single colonies are disregarded when reading plates after 18 hours at 37° C. The susceptibility (MIC) of the test organism is accepted as the lowest concentration of compound capable of producing complete inhibition of growth as judged by the naked eye. Like other polycyclic ether antibiotics, the present compound of the formula (I) typically shows Gram positive antibacterial activity, as well as activity against Treponema hyodysenteriae (the causative agent of swine dysentery).

Efficacy data for the compound of the formula (I) and its salts against coccidial infections in chickens is obtained by the following method. Groups of 3-5 ten-day old pathogen free white leghorn cockerel chicks are fed a mash diet containing the compound (I) or its sodium and/or potassium salt uniformly dispersed therein. After being on this ration for 24 hours each chick is inoculated per os with oocysts of the particular species of eimeria being tested. Other groups of 3-5 ten-day old chicks are fed a similar mash diet without compound (I) or its salts. They are also infected after 24 hours and serve as infected controls. Yet another group of 3-5 ten-day old chicks are fed the same mash diet without antibiotic and are not infected with coccidia. These serve as normal controls. The results of treatment are evaluated after five days in the case of E. acervulina, and six days for all other challenges.

The criteria used to measure anticoccidial activity consists of lesion scores of 0 to 4 for E. tenella after J. E. Lynch, "A New Method of the Primary Evaluation of Anticoccidial Activity", Am. J. Vet. Res., 22., 324-326, 1961; and 0 to 3 for the other species based on modification of the scoring system devised by J. Johnson and W. H. Reid, "Anticoccidial Drugs. Lesion Scoring Techniques in Battery and Floor Pen Experiments in Chicks", Exp. Parasit., 28, 30-36, 1970. Activity is measured by dividing the lesion score of each treated group by the lesion score of the infected control. In this test, the compound (I) and its cationic salts exhibit activity against Eimeria tenella, E. acervulina, E. maxima, and E. necatrix infections in poultry when incorporated into the mash diet of chickens at levels of about 10 to 100 ppm.

The present compound of the formula (I) is also generally useful in combination with certain other known anticoccidial agents, such as nicarbazin, 4,4'-dinitrocarbanilide or a naphthalenamine, as defined by Hamill et al., U.S. Pat. No. 4,582,822.

For the prevention or control of coccidiosis in poultry, the compound of this invention is orally administered to poultry in a suitable carrier. Conveniently, the medication is simply carried in the drinking water or in the poultry feed, so that a therapeutic dosage of the agent is ingested with the daily water or poultry ration. The agent can be directly metered into drinking water, preferably in the form of a liquid concentrate, or added directly to the feed as such, or, more commonly, in the form of a premix or concentrate of therapeutic agent in a solid carrier. The therapeutic agent can be in substantially pure form (e.g., the free acid, or a pharmaceutically-acceptable salt thereof), in assayed crude form such as wet or dry mycelium or dried whole broth. Suitable carriers are liquid or solid, as desired, such as water, various meals (for example, soybean oil meal, linseed oil meal, corncob meal) and mineral mixes such as are commonly employed in poultry feeds. A particularly effective carrier is the poultry feed itself; that is, a small portion of poultry feed. The carrier facilitates uniform distribution of the active materials in the finished feed with which the premix is blended. This is important because only small proportions of the present potent agents are required. It is important that the compound be thoroughly blended into the premix and, subsequently, the feed. In this respect, the agent may be dispersed or dissolved in a suitable oily vehicle such as soybean oil, corn oil, cottonseed oil, and the like, or in a volatile organic solvent and then blended with the carrier. It will be appreciated that the proportions of active material in the concentrate are capable of wide variation since the amount of agent in the finished feed may be adjusted by blending the appropriate proportion of premix with the feed to obtain a desired level of therapeutic agent.

High potency concentrates are blended by the feed manufacturer with proteinaceous carrier such as soybean oil meal and other meals, as described above, to produce concentrated supplements which are suitable for direct feeding to poultry. In such instances, the poultry are permitted to consume the usual diet. Alternatively, such concentrated supplements are added directly to the poultry feed to produce a nutritionally balanced, finished feed containing a therapeutically effective level of one or more of the compounds of this invention. The mixtures are thoroughly blended by standard procedures, such as in a twin shell blender, to ensure homogeneity.

For use in poultry, the use levels of the compound described herein will vary under different circumstances. Continuous low-level medication, during the growing period; that is, during the first 5 to 12 weeks for chickens, is an effective prophylatic measure. In the treatment of established infections, higher levels may be necessary to overcome the infection. The use level of the compound (I) in feed will generally be in the range of about 10 to 100 ppm. When administered in drinking water, the level which will be that which will provide the same daily dose of medication factored by the weight ratio of the average daily consumption of feed to the average daily consumption of water.

The activity of the compound of the formula (I) and its salts in the promotion of growth and/or increasing the efficiency of food utilization in swine or cattle can be measured directly by feeding test groups of animals various levels of the compound (I) or a salt in feed. Alternatively, British Patent Specification No. 1,197,826 details an in vitro rumen method for the evaluation of antibiotics in feeds.

For use in the prevention or treatment of swine dysentery, or in promoting growth and/or increasing the efficiency of feed utilization in cattle or swine the compound of the formula (I) or a salt is preferably administered as a feed additive. The feeds prepared according to methods fully analogous to those detailed above for the preparation of poultry feed, with the same concern for producing feeds in which the therapeutic agent is uniformly dispersed. The use level of the compound (I) in cattle or swine feed will generally be in the range of about 1 to 100 ppm. In ruminants the compound of the formula (I) can also be orally administered in the form of a bolus which is retained in the rumenoreticular sac, releasing the therapeutic agent at a substantially constant rate over a prolonged period of time, e.g., 4-8 weeks, providing a dose equivalent to that of the above daily dose in feed, i.e.: ##EQU1## Exemplary of such a controlled release bolus is that of Cardinal, U.S. Pat. No. 4,601,893.

The present invention is illustrated by the following examples. However, it should be understood that the invention is not limited to the specific details of these examples.

EXAMPLE 1 Fermentation of Actinomadura sp. ATCC 55080 Isolation of the Antibiotic of the Formula (I) as Sodium Salt

The Actinomadura sp. was initially grown by inoculating solid media on slants or Roux bottles with the ATCC 55080 culture, using ATCC medium No. 172, prepared and having composition as follows.

    ______________________________________                                                           Grams/liter                                                  ______________________________________                                         Glucose             10                                                         Soluble Starch      20                                                         Yeast Extract       5                                                          Casein Enzymatic Hydrolysate                                                                       5                                                          Calcium Carbonate   1                                                          Distilled water to 100 ml; pH to 7.0 with KOH;                                 Add Agar20                                                                     ______________________________________                                    

Meanwhile, 300 ml shake flasks were prepared using in each flask 100 ml of one or the other of the following media:

    ______________________________________                                                     Grams/                 Grams/                                      C'          liter    JDYTT         liter                                       ______________________________________                                         Cerelose    10       Cerelose      10                                          Soy Flour   10       Corn Starch   5                                           Corn        5        Corn Steep Liquor                                                                            5                                           Fermentation                                                                   Solids                                                                         Corn Starch 10       Casein Enzymatic                                                                             5                                                                Hydrolysate                                               Sodium Chloride                                                                            5        Cobalt Chloride                                                                              0.002                                       Cobalt Chloride                                                                            0.002    Calcium Carbonate                                                                            3                                           Calcium Carbonate                                                                          1                                                                  ______________________________________                                    

The medium-containing shake flasks were then sterilized at 120° C. and 15 p.s.i. (1.05×10⁴ kg/m²) for 30 minutes. After cooling, the medium was inoculated with a vegetative cell suspension scraped from the above Actinomadura sp. slant culture. The flasks were shaken at 28° C. on a shaker having a displacement of 1.25 to 2.5 inches at 150 to 200 cycles per minute (CPM) for four to five days.

Meanwhile, 5 liter fermentation vessels were prepared containing 3 liters of one of the above C' or JDYTT media or the following media:

    ______________________________________                                         UK1-2            Grams/liter                                                   ______________________________________                                         Cerelose         45                                                            Soy Flour        10                                                            Corn Steep Liquor                                                                               10                                                            Cobalt Chloride  0.002                                                         Magnesium Sulfate                                                                               0.10                                                          Calcium Carbonate                                                                               3                                                             Manganese Sulfate                                                                               0.10                                                          ______________________________________                                    

An antifoaming agent (polypropyleneglycol, P2000, containing 10% ethylene oxide by weight, 1 ml) was added, and the vessels were sealed and sterilized at 120° C. and 15 p.s.i. (1.05×10⁴ kg/m²) for 1 hour. The vessels Were then inoculated with one shake flask (ca 3% inoculum), and fermented for 120 to 168 hours at 30° C., stirring at 1700 revolutions per minute (RPM) with an air rate of one volume of air per volume of liquid per minute.

When the fermentation was completed (based on an antibiotic disc assay versus B. subtilis ATCC 6633) the fermenters were stopped and filtered at the natural pH with the aid of a diatomaceous earth. The filter cake was slurried in methanol, concentrated in vacuo, diluted with 2-3 volumes of water then extracted 2 X with 1/3 to 1/2 volume of either methylisobutyl ketone or n-butanol. The solvent layer was separated from the aqueous phase by aspiration or centrifugation, sparkled and concentrated in vacuo to yield the antibiotic of the formula (I) in crude form as a viscous oil.

The bioactivity of the broth and subsequent recovery streams can be followed by using a sensitive strain of Bacillus subtilis ATCC 6633 or Staphylococcus aureus ATCC 6538. The components in the broth and recovery streams can be visualized by thin layer chromatography (tlc) using Analtech silica gel GF plates employing ethyl acetate as eluant. The developed plates are sprayed with vanillin reagent (3 g vanillin in 75 ml ethanol and 25 ml 85% phosphoric acid) and heated to 80° C. The antibiotic product of the formula (I) appears as a red colored spot. The developed tlc plate can also be overlayed with agar seeded with either S. aureus or B. subtilis to which 2,3,5-triphenyl-2H-tetrazolium chloride monohydrate has been added and incubated at 37° C. for 16 hours to visualize the antibiotic (white spots against a pink background).

Scale-up in large fermentation vessels was carried out by preparing shake flasks containing 0.7 liters of C' or JDYTT medium. The shake flask inoculum was fermented for 5 to 7 days at 28° C., and used to inoculate a 200 liter fermentation vessel containing 100 liters of JDYTT medium, respectively. The fermentation, after proceeding for 7 to 10 days, was harvested. The whole broth was extracted with 33 liters of methyl isobutyl ketone at natural pH. The organic extract was separated on an alpha-DeLaval separator and concentrated under vacuum to yield the crude antibiotic of the formula I as an oil. The oil was chromatographed on silica gel, eluted first with hexane, then with CH₂ Cl₂, and finally with ethyl acetate. Product containing fractions were combined and rechromatographed using CHCl₃ /acetone as eluant and stripped to yield crude antibiotic of the formula (I). The crude was taken up in chloroform, extracted with dilute phosphoric acid and then with pH 9.0 phosphate buffer. The organic phase was dried (Na₂ SO₄), stripped, and the residue crystallized from diethyl ether/hexane and dried under high vacuum to yield 350 mg of the antibiotic of the formula (I) in the form of its sodium salt; m. p. 160°-162° C.; [alpha]_(D) ²⁵ =+16.3° (c=1, CH₃ OH).

Analysis calculated for C₅₀ H₈₅ O₁₇ Na: C, 62.58; H, 9.04. C, 62.16; H, 9.25.

Found:

¹³ C-NMR (CDCl₃) ppm (no. of attached H in parentheses):

180.60 (0), 106.70 (0), 99.53 (0), 98.47 (0), 96.61 (1), 94.74 (1), 88.74 (1), 84.59 (1), 84.09 (0), 83.85 (1), 83.20 (0), 80.77 (1), 80.46 (1), 80.25 (0), 80.25 (1), 79.64 (1), 74.33 (1), 73.72 (1), 67.48 (1), 61.70 (3), 61.47 (1), 60.30 (3), 59.88 (3), 58.96 (3), 56.81 (3), 46.26 (1), 45.97 (1), 45.35 (1), 40.74 (1), 39.34 (1), 36.85 (1), 32.66 (2), 31.89 (2), 31.14 (2), 29.94 (2), 28.95 (2), 28.25 (3), 27.69 (2), 26.69 (3), 25.75 (2), 24.36 (2), 22.52 (3), 18.52 (3), 13.24 (3), 12.59 (3), 12.53 (3), 12.03 (3), 11.55 (3), 11.49 (3) and 10.02 (3).

IR (KBr)cm⁻¹ :1610 (CO₂ ⁻).

EXAMPLE 2 Compound (I) in the Free Acid Form

The free acid form of the antibiotic of the formula (I) was prepared by vigorously shaking a chloroform solution of the sodium salt with an equal volume of hydrochloric acid at pH 2 in a separatory funnel. The phases were separated, and the chloroform layer was washed with water and then evaporated under vacuum to give the free acid; m. p. 109°-111° C.; [alpha]_(D) ²⁵ =+19.3° (c=1, CH₃ OH); IR (KBr)cm⁻¹ : 1700 (CO₂ H).

EXAMPLE 3 Compound (I) as Rubidium Salt for X-Ray Crystallography

The free acid form of the preceding Example (70 rag) was dissolved in 100 ml of CHCl₃. Rubidium carbonate (150 mg in 100 ml of water) was added and the mixture vigorously shaken in a separatory funnel. The organic phase was separated, washed with water, and evaporated to afford present title product as a white solid. This was recrystallized by slow evaporation from ether/hexane (3:1). A single crystal X-ray analysis by Dr. J. Bordner indicated that the antibiotic of the present invention was of the relative stereo-chemical formula (I) as depicted above. 

We claim:
 1. A process for preparing the compound of the formula ##STR2## or a pharmaceutically acceptable cationic salt thereof, wherein Me represents CH₃ comprising fermenting Actinomadura sp. ATCC 55080 under submerged aerobic conditions in an aqueous nutrient medium comprising an assimilable source of carbon and nitrogen and recovering said compound by separation from the fermentation medium.
 2. A process according to claim 1 wherein said separation step comprises filtering the fermentation medium and recovering a mixture of said compound and mycelium.
 3. A process according to claim 1 wherein said separation step comprises spray-drying or freeze-drying said fermentation medium and recovering said compound in crude form.
 4. A biologically pure culture of a strain of the genus Actinomadura having all of the identifying characteristics of ATCC 55080 said culture being capable of producing the compound of the formula ##STR3## wherein Me represents CH₃ in a recoverable quantity upon fermentation in an aqueous nutrient medium comprising assimilable sources of carbon and nitrogen.
 5. The culture according to claim 4 wherein said culture is in freeze-dried form.
 6. A culture according to claim 5 wherein said strain is Actinomadura sp. ATCC
 55080. 